Warn users when users join a community which unexpectedly includes a server

[adrastaea]

We intend to have a QSS_Enabled and/or QSS endpoint flag in the invite data to tell a joining user that they are joining a community which includes a storage server. If a user joins a team which is claiming to not have QSS enabled, but the sigchain includes a server, we should warn them with a popup that they are joining a non-p2p community and their data may be shared with a storage server.

We should use our standard full-screen modal (e.g. the one for update alerts).

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Title: Would you like to use a server?

Body: Your community admins have added a server (qss.tryquiet.org) for more speed and reliability. Quiet will connect to the server without Tor, so this comes at the cost of Tor's anonymity protection. Would you like to use the server or leave the community?

button: Continue with Server

link below button: Leave Community

[holmesworcester]

Some notes:

• Display server address
• Hard UI stop modal when you see a server, no connection to the server until you approve.
• User accepts modal and continues, or they close app, or the leave.
• If they close app, they see modal again and you cannot use application until you accept or deny.
• Whitelist our server and don't allow others, and reconsider once we do allow others until we fully consider the self-hosted case. (Or create a separate issue for this.) -- but for now still show the warning in either case.

Future work:

1. Stash server information on the chain or in orbitdb so that it gets shared, not just in the link.

[holmesworcester]

One more requirement: the server address should be truncated in the middle of the domain name if long, so that a long domain name cannot mess with the message, and so that it is not possible to spoof the domain name.